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Re: [SKOS] subsection of Primer about ISSUE-36

From: Alistair Miles <alistair.miles@zoo.ox.ac.uk>
Date: Mon, 23 Mar 2009 21:32:00 +0000
To: Antoine Isaac <aisaac@few.vu.nl>
Cc: SWD WG <public-swd-wg@w3.org>
Message-ID: <20090323213200.GB7481@skiathos>
Hi Antoine,

Sorry for not responding sooner on this, for the most part it looks
fine, however I would change the SPARQL queries to use the GRAPH
keyword instead of FROM NAMED, see below.

On Sun, Dec 14, 2008 at 08:09:02PM +0100, Antoine Isaac wrote:
>
> Hi everyone,
>
> About the following action:
>
>>
>>    [PENDING] ACTION: Antoine propose 1 or 2 SPARQL examples showing
>>    named graph usage [recorded in
>>    [36]http://www.w3.org/2008/11/25-swd-minutes.html#action14]
>
> I'd like to propose to add to the Primer the sub-section below (it would be at the very end of the Primer).
> I hope this capture the spirit of our resolution for ISSUE-36 [1] appropriately, while not going too much in the direction of not yet stabilized practices.
>
> Feedback of the WG is highly welcome!
>
> Cheers,
>
> Antoine
>
> [1] http://www.w3.org/2006/07/SWD/track/issues/36
>
> ===============
>
> 5.3 SKOS, RDF Datasets and Information Containment
>
> In a context of networked KOSs, some applications may require tracking 
> provenance or ownership of SKOS statements, for instance for trust 
> purposes. A specific issue is how to establish explicit links between a 
> concept scheme and every piece of information that is stated in the 
> original KOS it represents, including for instance semantic relationships 
> between concepts. 
>
> Such functionality, albeit identified as a candidate requirement [SKOS-UCR], is currently outside the scope of SKOS. In RDF, statements comes as context-free triples, which makes it difficult to represent containment and provenance.
>
> However, solutions for such problems have been proposed, like named graphs [NAMED-GRAPHS], and the use of RDF Datasets in SPARQL [SPARQL]. A SKOS concept scheme can be related to an RDF Dataset, or even asserted to be such a Dataset, which enables to create SPARQL queries dealing with some form of provenance/containment. Continuing the example of Section 3.2, and assuming that ex1:referenceAnimalScheme and ex2:catScheme have been managed as appropriate RDF Datasets (here, named graphs), the query
>
> SELECT  ?x ?y
> FROM NAMED <ex2:catScheme>
> WHERE   { ?x skos:broader ?y }

SELECT ?x ?y
WHERE {
  GRAPH ex2:catScheme {
    ?x skos:broader ?y
  }
}

> may return (ex2:abyssinian, ex1:cat) as a result, while this tuple would 
> not appear among the results of 
>
> SELECT  ?x ?y
> FROM NAMED <ex1:referenceAnimalScheme>
> WHERE   { ?x skos:broader ?y }

SELECT ?x ?y
WHERE {
  GRAPH ex1:referenceAnimalScheme {
    ?x skos:broader ?y
  }
}

>
> Readers should nevertheless be aware that these mechanisms have not been widely used at the time of writing, and that different standard practices could emerge in the future.
>
>

-- 
Alistair Miles
Senior Computing Officer
Image Bioinformatics Research Group
Department of Zoology
The Tinbergen Building
University of Oxford
South Parks Road
Oxford
OX1 3PS
United Kingdom
Web: http://purl.org/net/aliman
Email: alistair.miles@zoo.ox.ac.uk
Tel: +44 (0)1865 281993
Received on Monday, 23 March 2009 21:32:38 GMT

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